Fire-retardant and dye-receptive synthetic fibers

ABSTRACT

POLYESTER AND CELLULOSE TRIACETATE FIBERS ARE MADE DYE RECEPTIVE AND RESISTANT TO BURNING BY IMPREGNATING THE FIBERS WITH AN ORGANIC SOLVENT SOLUTION OF ANY OF CERTAIN POLYBROMINATED PHENOL DERIVATIVES. THE IMPREGNATED FIBERS ARE RESISTANT TO LOSS OF THE BROMINATED COMPOUND DURING LAUNDERING OR DRY CLEANING.

United States Patent m ABSTRACT OF THE DISCLOSURE Polyester and cellulose triacetate fibers are made dyereceptive and resistant to burning by impregnating the fibers with an organic solvent solution of any of certain polybrominated phenol derivatives. The impregnated fibers are resistant to loss of the brominated compound during laundering or dry cleaning.

BACKGROUND OF THE INVENTION This invention relates to a treatment of certain synthetic fibers with an organic solvent solution of a brominated phenol derivative to renderthose fibers both more readily dyed and more resistant to burning. It relates also to the treated fibers thereby obtained.

Fabrics and fibers of polyester or cellulose triacetate are commonly dyed with so-called disperse dyes which, it is thought, act by incorporation of the dye molecules directly into the fiber structure to form a solid solution. In order to facilitate this process, these fibers are treated with a dye assistant prior to or in the course of the dyeing process to make the fibers more receptive to the dye. According to one theory, the dye assistant swells the fibers and makes them more permeable to the dye molecules. Usually, this dye assistant is incorporated into the aqueous dyebath and the fiber or fabric is treated simultaneously with both the dye assistant and the dye. Some typical dye assistants are biphenyl, salol, o-phenylphenol, trichlorobenzene, benzoic acid, and methyl salicylate. However, this method of use is not practical for some compounds which are otherwise useful dye assistants because they produce spotting or uneven dyeing when they are put into the dyebath. For such compounds, a solvent solution pretreatment of the material to be dyed accomplishes the desired result.

In recent years there has developed an increasing urgency toward making textile fabrics more resistant to burning. This has been done by a surface treatment of the dyed fabric with one or more fire-retardant chemicals and it has also been done by incorporating a fire-retardant compound into a polymer fiber .as a plasticizer or merely as an additive. Fire-retardant monomers have been copolymerized into the polymer structure to obtain this effect. However, all of these methods are subject to characteristic disadvantages. Surface treatment of a fabric usually has only a temporary effect and the fire-retardant additive is rapidly lost when the fabric is laundered or dry cleaned. Additives physically mixed or chemically incorporated into the polymer usually detract from the properties of the polymer fiber so that while the fire-retardant effect may be relatively permanent, the fiber may be more brittle, of lower tensile strength, or with less resistance ot oxidative degradation.

3,749,600 Patented July 31, 1973 SUMMARY OF THE INVENTION It has now been found that a polyester or cellulose triacetate fiber is made both fire-retardant and receptive to dyeing with a disperse dye by impregnating the fiber with an organic solvent solution of a polybrominated phenol derivative of the group consisting of hydroxylated lower alkyl ethers of tribromophenol and tetrabromobisphenol A, mixed esters of phosphoric acid with lower alkylene polyols and tribromophenyl glyceryl ether, and tribromophenyl acetate. The terms lower alkyl and lower alkylene are used to define those radicals having 2-4 carbon atoms. Specific compounds of the group include:

2-(2,4,6-tribromophenoxy)ethanol 1-(2,4,6-tribromophenoxy)-2-propanol 3-(2,4,6-tribromophenoxy)-1,2-propanediol 1-(2,4,6-tribromophenoxy)-2-butanol 2,2-isopropylidenebis(2,6-dibromo-p-phenyleneoxy) diethanol 1,1-isopropylidenebis(2,6-dibromo-p-phenyleneoxy)di- 2-propanol 2,4,6-tribromophenyl acetate bis(2-hydroxypropyl) 2-hydroxy-3-(2,4,6-tribromophenoxy)propyl phosphate bis[2-hydroxy-3-(2,4,6-tribromophenoxy)propyl] 1 Z-hydroxyethyl phosphate Any inert organic solvent with capacity to dissolve an eflective amount of the brominated compound is operable, but for even distribution of the compound in the fiber, a solvent having a boiling point above the melting point of the compound is desirable. Aliphatic and aromatic hydrocarbons and their chlorinated derivatives are preferred solvents and perchloroethylene is a particularly advantageous solvent.

DETAILED DESCRIPTION For efiective fire-retardancy and good dye-receptivity, sufficient brominated compound to provide about 1-10 percent by weight of bromine is desirably impregnated into the fiber. The impregnating process consists essentially of merely soaking the fiber in the solvent solution, preferably at 50 l50 C., and then drying the impregnated fiber to remove the solvent. The treated fiber can then be passed into a conventional aqueous dyebath for dyeing.

A particular and surprising advantage of the present invention is the fact that the brominated compounds listed above not only need not be removed from the dyed material by the conventional scour or other treatment, but in fact they are so firmly held in the fiber that it is highly resistant to loss of bromine content during laundering and dry cleaning operations. The scour step following the dyeing process can thus be eliminated entirely or modified to a briefer or milder treatment for surface color removal only.

When treated by this process, the fiber typically contains about 1-1() percent by weight of bromine, preferably about 2-6%, and it is thereby rendered substantially and permanently more resistant to burning. Carpeting, for example, treated in this Way will pass the so-called tablet test. Being eificient dye assistants, the brominated compounds listed also provide fabrics dyed with the same depth of shade as materials dyed in the same Way using a conventional dye assistant such as biphenyl.

These new fire-retardant dye assistants can be used with any of the disperse dyes conventionally used to dye polyester and cellulose triacetate fibers. Representative disperse dyes are C.I. (Color Index) Disperse Red 1, Cl. Disperse Blue 55, CI. Disperse Red 60, CI. Disperse Yellow 23, and Cl. Disperse Red 55.

The term polyester is used herein in its usual sense to mean highly polymeric, essentially linear polyester resins made by the reaction of a dicarboxylic acid or ester with a diol in the presence of an esterification or ester interchange catalyst. Illustrative dicarboxylic acids are malonic, succinic, adipic, azelaic, maleic, fumaric, hydromuconic, isophthalic, terephthalic, and cyclohexanedicarboxylic acids. Representative diols are ethylene glycol, propylene glycol, butylene glycol, and 1,6-hexanediol. The common commercial polyester resins are polyethylene terephthalate and polyethylene terephthalate modified by inclusion of minor proportions of a different glycol or dicarboxylic acid during the polyesterification process. The polyester used in the examples was polyethylene terephthalate.

Cellulose triacetate is used in its usual sense to mean the fully esterified material where there has been little or no hydrolysis of the acetate groups on the cellulose molecule.

Example 1 A number of pieces of polyester cloth were wet by immersing in a 6 weight percent solution of 2-(2,4,6- tribromophenoxy)ethanol in perchloroethylene at 90 C. Excess solution was removed in a centrifuge and the samples of cloth were dried at 121 C.

The dried cloth contained about 6% by weight of the brominated compound (equivalent to 3.2% Br). When the treated cloth was dyed in an otherwise conventional aqueous bath containing C.I. Disperse Blue 55 but with no dye carrier present, dyeing of the same depth of shade was obtained as in common practice using a conventional carrier. Both the dye cloth and the treated cloth before dyeing exhibited roughly 50% reduced flammability as compared to untreated and conventionally dyed cloth, using as the comparative test a procedure wherein a strip of cloth is held in a semicircular arc with the two ends extending downwardly, one of the ends is ignited, and the point on the cloth strip where the flame goes out is observed. The length of the burn is then a measure of the relative flammability of the cloth.

Example 2 Swatches of polyester cloth treated by the process of Example 1 to contain about 6 percent by weight of 2- (2,4,6-tribromophenoxy)ethanol were subjected to repeated washing cycles in a home automatic washing machine with Tide detergent. Another group of swatches which had been treated in the same way were put through a number of cleaning cycles in an automatic dry cleaning machine using perchloroethylene as the cleaning fluid. In each case, several swatches were analyzed for bromine content at intervals throughout the cleaning processes to determine how effectively the brominated compound was retained in the polyester fiber. Percentages given are averages of several analyses.

It is seen that the treated cloth was highly resistant to loss of brominated compound in both cleaning processes, particularly the aqueous detergent wash.

Examples 3-9 Swatches of polyester cloth were treated as described in Example 1 with perchloroethylene solutions containing similar concentrations of the following compounds:

1- 2,4,6-tribromophenoxy -2-propanol 1- 2,4,6-tribromophenoxy) -2-butanol 3- 2,4,6-tribromophenoxy 1 ,2-propanediol 2,4,6-tribromophenyl acetate 2,2"-isopropylidenebis 2,6 dibromo-p-phenyleneoxy) The treated and dried swatches in each case were similarly receptive to dyeing and resistant to burning as those of Example 1.

In the same way, samples of polyester fabric treated by this process with similar concentrations in other chlorinated solvents as previously defined of the brominated compounds of the examples are rendered dye receptive and resistant to burning.

Comparable results are obtained when the procedures of the above examples are repeated using cellulose triacetate cloth in place of the polyester although slightly higher percentages of bromine content are required in the triacetate to obtain the same level of fire-retardancy.

Example 10 Samples of conventionally dyed polyester carpet were soaked in a perchloroethylene solution containing 6% by weight of 2-(2,4,6-tribromophenoxy)ethanol and dried as described in Example 1. The treated polyester fabric contained about 6% by weight of the brominated compound and easily passed the tablet test (DOCFFI70), the burned area being only about 1 inch in diameter. Untreated samples of the same carpet were entirely consumed when subjected to this test.

We claim:

1. A fire-retardant and dye-recptive polyester or cellulose triacetate fiber containing about 1-10 percent by weight of bromine as at least one brominated compound selected from the group consisting of hydroxylatedlower alkyl ethers of tribromophenol and tetrabromo-bisphenol A, mixed esters of phosphoric acid with lower alkylene polyols and tribromophenyl glyceryl ether, and tribromophenyl acetate.

2. The fire-retardant and dye-receptive fiber of claim 1 wherein the brominated compound is at least one of 2-(2,4,6-tribromophenoxy)ethanol,

1-(2,4,6-tribromophenoxy)-2-propanol,

1-(2,4,6-tribromophenoxy)-2-butanol,

3-(2,4,6-tribromophenoxy)-l,2-propanediol,

2,2'-isopropylidenebis(2,6-dibromo-p-phenyleneoxy) diethanol,

1,1'-isopropylidenebis(2,6-dibromo-p-phenyleneoxy) di-Z-propanol,

2,4,6-tribromophenyl acetate, and

bis(2-hydroxypropyl)-2-hydroxy-3-(2,4,6-tribromophenoxy)propyl phosphate.

3. The fiber of claim 2 wherein the brominated compound is 2-(2,4,6-tribromophenoxy)ethanol.

4. The fiber of claim 2 wherein the brominated compound is 1-(2,4,6-tribromophenoxy)-2-propanol.

5. The fiber of claim 2 wherein the brominated compound is l-(2,4,6-tribromophenoxy)-2-butanol.

6. The fiber of claim 2 wherein the brominated compound is 3-(2,4,6-tribromophenoxy)-1,2-propanediol.

5 6 '7. The fibel: of clairn 2 wherein the brominated com- References Cited gig/1313i;fhiiiisopropyhdenebis(2,6-d1b1-omo-p-pheny1ene- UNITED STATES PATENTS 8. The fiber of claim 2 wherein the brominated com- 2,660,543 11/1953 Walter 6t pound is 1,1'-iSOprOpy1idenebis(2,6-dibromo-p-pheny1ene- 5 3,321,330 5/ 1967 M hney 117-136 oxy di-Z-propanol.

9. The fiber of claim 2 wherein the brominated com- WILLIAM MARTIN Pnmary Exammer pound is 2,4,6-tribr0mophenyl acetate. DAVIS, Assistant Examiner 10. The fiber of claim 2 wherein the brominated com- U 5 c1 X R pound is bis(2-hydr0xypropy1) 2-hydr0xy-3-(2,4,6-tri- 10 bromophenoxy)propy1 phosphate. 8173; 117138.8 F, 144; 252-81 

